Method of making bearing and gasket material



Patented Sept. 13,1938 I METHOD OF MAKING BEARING AND GAS- KET MATERIALEdwin F. Kiei'er, Cleveland, Ohio, assignor, by

mesne assignments, to Union Carbide and Carbon Corporation, acorporation of New, York No Drawing. Application July 21, 1934, I SerialNo. 736,344

, '7 Claims.

This invention relates to a method of making porous structures andespecially impregnated po- 'rous structures suitable for use as gaskets,bearings, or the like.

An object of this invention is to provide a hard, porous base or matrixwhich is capable of being impregnated with softer materials. Anotherobject of this invention is to provide a method of producing a base ormatrix having a largev number of fine pores. Still another objectis toprovide a, hearing or gasket of porous copper im-' pregnated with softermaterials. The above and other objects together with the novel featuresof this invention will be apparent from the following description.

To achieve the above-enumerated objects in accordance with thisinvention, a matrix is first prepared from a suitable metal or itsoxide. Any oxide of ametal may be used which is capable of being reducedand at the same time of being formed into a coherent mass in the mannerof a porous honeycombed structure. However, it is preferred to employcopper and/or copper oxide in forming a matrix because of inherentcharacteristics peculiar to this metal. Desirable results are obtainedwith a comminutedmixture of copper and copper oxide, but copper orcopper oxide alone is also suitable. The copper and copper oxide may befinely divided or pulverized and intimately mixed with a suitablereducing agent. Ammonium chloride provides the necessary chemicalconstituents to perform the reducing reaction and also acts as a binderto cause the copper and copper oxide particles to adhere closelytogether. The limiting proportions of NHsCl are to 18% but I prefer touse from 4' to 15%. Above-18% there is a decided tendency for the formedarticle to crack and deform. Below 4% reaction will occur most speedilyand efliciently."

An inert atmosphere, from which oxygen has been excluded, materiallyaids in making the reaction complete, and it has also been found that anincrease in pressure above atmospheric will tend to assist in speedingthe baking process. The baking acts to sinter the molded sheets of wellConsiderable ammonium chloride is volatilized and does not enter thereaction. However, the volatilized ammonium chloride serves as a,blow-'ing'agent to produce porosity as well as to prevent oxidation. Thisresults in the sheets or molded material becoming honeycombed or filledwith pores. The copper particles become fused together at intermediatepoints throughout the mass and. form a substantially rigid foraminousmatrix which is not subject to crumbling nor to crushing under moderatepressure.

When the sheets have cooled, they are suitable for use as gaskets intheir then existing form. However, superior gaskets may be made byimpregnating the porous matrices with gums, resins, or waxes, or withsofter metals such as tin or lead.

I have found that lead and lead-tin alloys are well adapted for thisimpregnation. This is best applied by soaking the porous matrix inmolten lead or lead-tin alloy. The amount of lead taken up may vary from6% for copper having a low porosity to as high as 105% for copper havinga higher porosity. When resins 'or the like are used as impregnatingmaterial, the percentage will be much lower. Other suitable materialsmay be used for impregnation, such as rubber, vinyl polymers, phenolformaldehyde condensation products, and the like. In nearly allinstances I prefer to use the largest amount of impregnating materialthat the foraminousmatrix will take up; that is, the foraminous matrixis preferablysubstantially saturated with the impregnating material. Inmost cases immersion in the molten material is suflicient. However, ifthe introduction of more material is required, or if the material isviscous and does not penetrate with ordinary soaking, pressure methodscan be resorted to.

A matrix of copper which has been prepared in accordance with thisinvention and impregnated with lead or tin or alloys of soft metals isadmirably suited to. serve as a. bearing material. The relatively hardstructure of-the matrix withstands the high pressures which areexperienced in the contact of metal parts movable in relation to otherand cooperating parts. The softer impregnated material servesas anantifriction stance tends to iiow to the surface of the sheet andprevents leaks from occurring ,in glands, stufiing boxes, and betweenmetal edges, as in engine blocks and tank covers. a

Although a preferred method and resulting gasket and bearing materialshave been described, it will be understood that changes may be madewithout departing from the principles or scope of this invention.

I claim:

1. A method of making a porous structure comprising the steps of mixingan unalloyed finely divided oxide of copper with an ammoniacal salt;molding the mixture to a desired shape; and sintering the moldedingredients to form a porous mass of substantially pure copper.

2. A method of making a. porous structure comprising the steps of mixingcomminuted copper and copper oxide with ammonium chloride; molding themixture to a desired shape; and heating the molded ingredients tocreatea coherent porous material.

3. A method of making an impregnated bearing comprising the steps ofmixing an unalloyed pulverulent oxide of copper with ammonium chloride;molding the mixture; heating the molded ingredients to form a porousstructure of substantially pure copper; and introducing a softer metalinto the pores.

d. A method of making an impregnated gasket comprising the steps ofmixing unalloyed pulverulent copper with ammonium chloride; molding themixture; heating the molded ingredients to form a porous structure ofsubstantially pure copper; and introducing an alloy of lead and tin intothe pores.

5. A method of making an impregnated material suitable for use asgaskets, hearings or the like, comprising, the step of mixing comminutedcopper and copper oxide with 4 to 18% ammonium chloride; molding themixture; heating the molded ingredientsin a reducing atmosphere to forma foraminous structure; and introducing a softer substance into thepores.

6. A methodof making an impregnated material comprising the steps ofmixing an unalloyed pulverulent oxide of copper with a combined blowingand reducing agent; molding the mixture; heating the molded ingredientsin a reducing atmosphere to produce a sintered structure ofsubstantially pure copper; and introducing from 6 to 105%. by weight ofan alloy predominantly lead into the pores.

7. A method of making an impregnated material comprising the steps ofmixing a pulverulent oxide of copper with ammonium chloride; molding themixture; heating the molded article in a reducing atmosphere to form aporous structure; and introducing a lead-tin alloy into the pores.

